PSN-L Email List Message

Subject: Re: distortion on geophones
From: "tdick" dickthomas01@.............
Date: Mon, 28 Jun 2004 12:37:11 -0500





> Tom,
>=20
> This looks like an electrical problem rather then a problem with the =
sensor.
> Is the signal from the sensor going through one of my Amp/Filter =
boards? If
> it is you may want to send it back to me so I can check it out.
Larry I got several comments that changed my thinking and you may be =
right. I originally thought it was water in the bottom of the hole that =
the geophones were buried in. The geophones are in a 3x3 block of wood, =
in a 4 inch PVC pipe sealed on both ends and about four feet down -- =
very near the surface level of a lake 15 ft away. I noticed the problem =
about the time the rains started here in early April . But I was =
concentrating on local stuff. About that time I also changed my =
filtering -- trying to get a better display for a Internet site. Last =
night the two earthquakes- Illinois & Alaska showed an interesting =
contrast.=20

See all six Alaska and  Illinois unfiltered  =
http://Dad.bachcottage.com/June 28/raw pics&data . The more intense =
Illinois quake seems more distorted, even on the homemade vertical and =
Lehman's while not so on the Alaskan quake. If I am doing the filtering =
right, it seems to filter out on the homemade vertical and Lehman's -- =
see files unfiltered-filtered in same folder. If you have time,  look =
over this folder -- and any other stuff on this disk you have time -- I =
even enclosed raw data and individual event files. All electronics are =
yours. I did remove the jumpers on the amp board.








 

> Tom,
>
> This looks = like an=20 electrical problem rather then a problem with the sensor.
> Is the = signal=20 from the sensor going through one of my Amp/Filter boards? If
> it = is you=20 may want to send it back to me so I can check it out.
Larry I got = several=20 comments that changed my thinking and you may be right. I originally = thought it=20 was water in the bottom of the hole that the geophones were buried in. = The=20 geophones are in a 3x3 block of wood, in a 4 inch PVC pipe sealed on = both ends=20 and about four feet down -- very near the surface level of a lake 15 ft = away. I=20 noticed the problem about the time the rains started here in early April = ..=20 But I was concentrating on local stuff. About that time I also = changed my=20 filtering -- trying to get a better display for a Internet site. Last = night the=20 two earthquakes- Illinois & Alaska showed an interesting = contrast.=20
 
See all six Alaska and  = Illinois=20 unfiltered  http://Dad.bachcottage.com/June=20 28/raw pics&data . The more intense Illinois quake seems more = distorted,=20 even on the homemade vertical and Lehman's while not so on the Alaskan = quake. If=20 I am doing the filtering right, it seems to filter out on the homemade = vertical=20 and Lehman's -- see files unfiltered-filtered in same folder. If you = have time,=20  look over this folder -- and any other stuff on this disk you have = time=20 -- I even enclosed raw data and individual event files. All = electronics are=20 yours. I did remove the jumpers on the amp board.
 
 

[ Top ] [ Back ] [ Home Page ]